Nitric oxide (NO) has been implicated in many physiological processes including the modulation of neural networks in vertebrate and invertebrate olfaction. The Manduca sexta antennal lobe (AL) is a promising system for studying mechanisms of nitrergic neuromodulation, as many characteristics of this system have been thoroughly detailed. Based on preliminary immunohistochemical, NO fluorescence, and electrophysiological data, the hypothesis of this study is that NO is involved in modulating the strength of inhibitory synaptic transmission in the AL. NO may be modulating inhibition either indirectly, by affecting the excitability of GABAergic LNs, or directly, by modulating GABA receptors. Therefore, the first aims of this study are to elucidate which AL neurons are affected by NO through intracellular recordings and pharmacology, and to characterize the features of these cells, including their morphology and/or soluble guanylyl cyclase (sGC) expression. Next, multi-unit extracellular recordings will be completed to confirm that NO is involved in modulating inhibition in populations of AL neurons, and also to test how much of this modulation is due to sGC signaling. Finally, to further study how NO could be affecting GABA signaling, GABA receptors will be cloned and localized and their expression pattern characterized. These results are crucial for understanding links between inhibitory processing and NO signaling in the AL.